In the July 4, 1996, issue of Nature, Santer et al. reported a
climate model simulation of the combined effects of greenhouse gases and
anthropogenic sulfate aerosols that suggested a "fingerprint" of
anthropogenic influence on the atmosphere. (See Nicholls and Santer articles,
Global Climate Change Digest, Prof. Pubs./Gen. Interest, Aug. 1996.)
This study provides further evidence of human influence, but employs less
restrictive modeling assumptions than used by Santer et al. and a longer data
set for comparison (1961-1995), and also adds the effects of radiative forcing
by changes in stratospheric ozone. Results support the hypothesis of an
anthropogenic effect on atmospheric vertical temperature structure as a result
of the changing concentrations of greenhouse gases, stratospheric ozone, and
possibly sulfate aerosols. Discusses several limitations of the work; most
critical is that the estimate of natural atmospheric variability is based on the
model, and may be in error.

In a previous issue of Climatic Change, Brunner argued that the
mandate of the U.S. Global Change Research Program to "produce information
readily usable by policymakers" is incompatible with the program's current
emphasis on developing comprehensive predictive models of climate change and its
impacts, and Edwards rebutted his argument. (See Global Climate Change
Digest, Prof. Pubs./Of Gen. Interest, Mar. 1996.) In this paper, Shackley
says the real issue is communicating to the public that any commitments made
must necessarily be a blend of social, political and scientific choices, because
our understanding of natural and social systems is incomplete. This would open
the door to wider public involvement in developing commitments, although it is
not clear whether our current political culture can embrace such openness and
greater sharing of power and responsibility.

One point made by Brunner in his reply to Shackley is that the "policymakers"
who need readily usable information include citizens around the world who are in
a position to make discisions for their own households, businesses and
non-governmental organizations, and to influence public policies at all levels
of governmentthrough passive resistance if nothing else.

The comment by Edwards emphasizes that both preceding essays have ignored
the most important actor with respect to the public  the media. He
proposes ways of building public trust in public science and policy bodies, and
generating a sense of urgency in the public. One is for the media to give equal
weight to consensus knowledge, and not focus exclusively on conflicts 
whether of personalities, political views, or scientific work.